Conventionally, in recording the addresses of positions for drilling holes in a printed circuit board according to a layout pattern as a preliminary step for automatically drilling holes for mounting component parts and for other purposes in a printed circuit board, each position was picked up from a pattern sheet by a human operator on a flat table with the aid of an X-Y digitizer. However, this process was highly laborious and time-consuming, yet was no way free from human errors.
It is conceivable to make use of advanced pattern recognition techniques for such a purpose but none of them have so far been applied successfully to such an application.
Another problem arising in the process of identifying and recording special points in a pattern with manual means is the difficulty of ascertaing the accuracy of the identified and recorded special points; there must a good way of making sure that there is no omission or error in the record.
Conventionally, such checking work was carried out by reading the perforated tape into which the identified addresses are recorded and plotting them on an automatic drafting machine or an X-Y recorder. But due to the nature of such a machine the plotting work was substantially time-consuming and caused a substantial slow-down in the otherwise highly automated process of making a printed circuit board.